The abrasive portion of a honing tool is the working portion of the tool as it is this portion of the tool which engages a particular workpiece under pressure during a honing operation and removes material therefrom until the desired final diameter of the workpiece has been achieved. As stock is being removed from a workpiece during a honing operation, metal chips and shavings have a tendency to load or stack up between the protruding abrasive particles on the honing tool, such build-up eventually leading to galling or scoring of the honed work surface. This is a continuing and on-going problem in many honing operations and the accumulation or adherence of such stock material between the abrasive particles is particularly true of ductile type materials such as stainless steel which produce long stringy chips or shavings during the honing process. Typically, such long stringy chips will fill up or clog the spaces between the protruding abrasive particles on the tool and then, after they have been hardened by compaction through the honing action itself, enough heat is eventually generated during honing that these chips or shavings will actually weld and bond themselves to the bonding matrix between the adjacent abrasive particles thereby causing galling or scoring of the honed work surface as the honing operation continues. Also, this stock material build-up reduces the cutting effectiveness of the abrasive particles and, once the abrasive particles wear to the same surface level as the stock build-up between such particles, any effective cutting action is eliminated. This phenomena therefore not only diminishes the quality of the finished work product but it also diminishes the overall service life of the tool and eventually leads to the termination of such tool as an effective cutting member.
Various means have been utilized in an effort to reduce and minimize the occurrence of having stock material build-up and collect between the abrasive particles of a honing tool thereby causing the aforementioned problems. For example, U.S. Pat. No. 4,155,721 discloses a dual bonding process for making single layered grinding tools wherein a metallic substrate is pre-etched so as to suitably cavitate the substrate surface prior to plating. Etching is believed to create small cavities in the substrate surface, each such cavity being adapted to individually receive a portion of an abrasive particle. This arrangement provides a stronger mechanical bond between the abrasive particles and the metal plated surface of the substrate so that at least a portion of the abrasive particles are recessed below the shear plane. This process further includes a second plating step wherein a second metallic bond matrix can thereafter be applied over the first metal coating to prevent stock build-up and adherence to the bond matrix between the abrasive particles. This second plating bath is comprised of metal ions only and, when the type and thickness of this second coating of metal is properly selected for the intended application of the tool, this second coating of metal between the abrasive particles helps to prevent glazing of the cutting edge of the tool due to the same stock build-up between the abrasive particles as previously explained.
U.S. Pat. Nos. 4,832,707; 4,973,338; and 4,868,069 likewise disclose various metal-bonded tools and methods for manufacturing the same including various anti-static and abrasion-resistant coatings for use with such abrasive products to decrease the incidences of stock build-up between the abrasive particles thereby improving the overall quality of the finished work product, including grinding efficiency and finishing accuracy. More particularly, U.S. Pat. No. 4,832,707 discloses a method of manufacturing a metal-bonded tool which uses diamond particles as the abrasive material for high efficiency grinding. This patent specifically addresses the problem associated with the grinding chips accumulating in the hollows formed within the bond holding the abrasive particles to the particular substrate and attempts to solve such problem by regulating the quantity of the carbon or graphite and the size of such precipitates in the bond.
U.S. Pat. No. 4,973,338 likewise attempts to reduce the incidence of build-up or clogging of the abrasive surface by treating the coated abrasive materials with an appropriate amount of a quaternary ammonium anti-static compound comprising about 15 to about 35 carbon atoms in a molecular weight not less than about 300. It has been found that coated abrasive materials, thus treated, have a combination of anti-static, lubricity and anti-loading characteristics which provide improved abrading efficiency and longer abrading life.
U.S. Pat. No. 4,868,069 discloses a method for improving the abrasion resistance of various substrates wherein the substrate is coated with a relatively soft metal matrix in which abrasion-resistant grit particles are embedded. The coating comprises abrasion-resistant particles that protrude from a metal matrix having a surface that is hardened relative to the bulk of the metal matrix, the coating being metallurgically bonded to the substrate. Embedding grit particles in the hardened coating prevents the grit particles from dislodging and it also prevents catastrophic cracks from developing in the coating.
Although all of the above-identified known prior art processes appear to address a similar type problem, namely, accumulation and adherence of stock build-up between the abrasive particles in the substrate as well as the destruction or plastic deformation of the bond therebetween with a resultant deterioration of finishing accuracy and quality, none of the known processes include the use of a nickel/Teflon or other metal or metal alloy composite material having a lubricant type substance occluded therewithin as an anti-galling agent for applying to and coating over the top of the bond already established between the plated abrasive particles on a honing tool as previously explained. The self-lubricating or friction reducing characteristics associated with Teflon particles or other suitable lubricating agents as will be hereinafter further explained in combination with the nickel or other metal or metal alloy material contained in the composite coating material produces both an anti-stick, anti-galling coating surface as well as a strong, abrasive resistant coating which adheres to and becomes part of the underlying bond and is capable of withstanding the forces and stresses of a honing operation without destruction and/or deformation. For these and other reasons, the present process differs both composition wise and application wise from the bonding processes disclosed in the known prior art.